Two of the biggest reasons are that 1) chronic alcohol intake damages the testosterone-producing Leydig cells, and 2) long- term use of alcohol stimulates enzymes in the liver that convert testosterone into estradiol; it also inhibits the manufacture of androgen receptors.

Researchers examined how acute alcohol ingestion affected testosterone levels after resistance exercise. In the test, eight men ages 21–34, all experienced in strength training, did 6 sets of squats with a weight at which they could just manage 10 reps with two-minute rest periods. Ten minutes after completing their last set, they were given either a placebo or 1.09g alcohol per kg of body weight—that’s about 10g (.35 oz) of alcohol per drink.

Researchers found no change in concentration of estradiol, cortisol, or SHBG in response to alcohol intake. But here’s the shocker: Total testosterone and free testosterone were elevated significantly immediately afer exercise for both conditions. At 140–300 minutes post-exercise, total and free testosterone levels as well as free androgen index were significantly higher for the alcohol group compared to the placebo. Hold on, though, before you head to the nearest bar afer working out: Researchers suspect that alcohol actually destroys receptors that testosterone can attach itself to, which is why the concentration of testosterone in the blood rises.

Having an occasional drink isn’t going to adversely affect you—but long-term use of alcohol is clearly bad for muscle gains. – FLEX